1. Field
The present disclosure relates generally to manufacturing and, in particular, to a method and apparatus for laser welding.
2. Background
Laser welding is a technique that may be used to join multiple pieces of metal through the use of a laser. A laser beam may provide a concentrated heat source to weld different metallic parts to each other. Laser welding may be performed using various types of lasers including solid state and gas lasers. The use of a laser allows for narrow and/or deep welds. Further, the use of a laser also may provide for high welding rates. Laser welding is typically used in high-volume applications such as in the aircraft and/or automotive industry.
Laser welding may be used to weld metal components such as those comprised of carbon steel, stainless steel, aluminum, and titanium. One advantage of laser welding may be the capability to join metal components such as scrap pieces of metal for the purpose of “scrap reduction” and formation of parts rather than machining these parts from larger pieces of raw materials.
The use of laser welding for manufacturing aircraft parts and aircraft may be useful in reducing the weight of aircraft. Laser welding may be used in place of riveting when joining large metal fuselage parts to each other. These parts include, for example, stringers used in metal fuselages. Using laser welding provides an advantage over rivets, because laser welding results in less weight when manufacturing aircraft.
For example, in addition to eliminating the use of rivets, the use of a filler metal between rivet parts also may be eliminated. As a result, the structure of an aircraft may be reduced by around five percent using laser welding instead of rivets. Further, a welded joint formed using laser welding may provide greater compressive and shared strength even though this type of joint is lighter. In addition, laser welding also may have a lower cost than the use of rivets. A further advantage of using laser welding to join parts to each other is that laser welded parts are less susceptible to corrosion.
Typically, the speed of welding is proportional to the amount of power supplied to the laser as well as the type and thickness of the parts being welded. Further, the speed at which laser welding may occur also may be limited by a number of different factors. For example, when welding titanium, it is desirable to prevent air from contacting molten titanium.
Unwanted gases in the air may attack the metal and cause contamination in the molten titanium during a welding process. This type of contamination may occur if the hot metal is not kept away from air until the titanium is cool enough. This type of discoloration is undesirable for aesthetic purposes.
Further, the contamination may be identified by discoloration, which may indicate a presence of adverse effects to metal properties in the titanium. Contamination of the titanium with air during welding can cause significant reduction in ductility and fracture toughness. This condition may lead to premature cracks and early fatigue failures.
One manner in which air may be prevented from contacting the molten titanium is to perform the laser welding in a vacuum. Although this type of process may be suitable for preventing discoloration, vacuum environments may be impractical based on the size of the part. Another technique involves introducing an inert gas to prevent air from contacting the titanium until the titanium is cool enough. This type of process, however, may slow down the speed at which welding can occur for titanium.
Therefore, it would be advantageous to have a method and apparatus that overcomes the problems described above.